Extensometer.



` W. J. TRIETC/H,

EXTENSOMETEH.

APPLICATION FILED ocT. I3, 1911.

yLSG-0,790. w Patented Apr.15,1'919.

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W. 1. TRETCH..

EXTENSOMETI-IH. APPLICATION FILED ocr. I3. 19,17.

Patented Apr. 15, 1919.

2 SHEETS-SHEET 2 mx v VIIIIIIIIIIIIIHIIH INVENTOR ATTORNEYS ITED STATES AT @FFQE i WILLIAM J. TRETCH, 0F PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO RIEHLE BROS. TESTING MACHINE C0., OI-l PHILADELPHIA, PENNSYLVANIA, A CORPORATION 0F PENNSYLVANIA.

EXTENSOMETER.

Speciiicaton of Letters Patent.

Patented Apr. 1,5, 1ere.

Application led October 13, 1917. Serial No. 196,362.

To all whom t may concern: y

Be it known that I, WILLIAM J. TRETGH, a citizen of the United States, residing in the city and county of Philadelphia, State of Pennsylvania,'have invented a new and' use* ful Extensometer, of which the follo-wingis a specification. Y

My invention consists of a novel exten` someter for the measurement of deformations in materials under stress, and wherein provision is made for compensating for any variations in the amounts of strain thatmay occur in opposite sides of the specimen under examination. f y

A further obj ect of my invention is to `devise a novel construction and arrangement of a movable frame and a iiXed frame, the movable frame being attached to the specimen to be stressed and being provided with an arm which rests against the plunger of an indieating dial. 1 A further object of my invention is to devise a novel manner of mounting the dial so that it may be readily adjusted so that the instrument will read correctly when `it is calibrated. i

A further object of my invention is to devise novel means for enabling the points of attachment to be brought the proper distance apartfor the quick` and convenient attach-` ment of the extensometer to the specimen.

A further object of my invention is to de` vise a novel construction of adouble pointed marking block whereby the specimen can be accurately and quickly marked the required distance apart ready to receive the eXtensometer.

`Other objects and advantages of the in'- vention and novel features of construction will hereinafter more clearly appear in the detailed description of the invention.

For the purpose of illustrating my invention, I have shown in the accompanying drawings a typical embodiment of it which is `at present preferred by me, since this embodiment will give in practice satisfactory and reliable results, although it is to be understood that the various instrumentalitiesof which my invention consists can be variously arranged and organized and that my invention is not limited to the precise arrangement and organization `ot' these instrumentalities 'as herein `shown and described. V Figure 1 vrepresents a front elevation-ofi an eXtensometer embodying my invention, with certain of the fastening screws removed for thesake of clearness of illustration. y

Fig. 2 represents a section on line 2 2 of Fig. l. Y

Fig. 3 represents'a section on line 3-3 of Fig. 2. `Fi Fig.

Fig. 5 representslin4 perspective, a marking device for the specimens.

Fig. 6 represents a section on line 6 6 of Fig. 7. r r

Fig. 7 represents a section on line 7-7 of Fig. 6. l

SimilarV numerals of reference indicate cor responding parts.

Referring to the drawings l designates the top or movable frame and 2 designates the lower or swivel frame which is carried by a strut 3. The movable frame 1 comprises a yoke 4, the .arms of which straddle the strut 3 and. are fulcrumed there# on by means of the fulcrum pivots and locking screws 6.

7 `designates the specimen clamp screws which are in threaded engagement with the arms of the yoke 4 and are provided with cone-'shaped ends to engagethe walls ofthe apertures formed in the Yspecimen by `the markingl device seen in Figs 5 to 7 inclusive. The outer'ends of the specimen clamp screws are enlarged and arepreferably knurled in order to facilitate their adjustment. EX- tending fromtheyoke 4 and preferablyintegral therewithlis an arm 8 which is provided Vwith-a Iring or thumb piece 9. The strut 3 is bifurcated'to permit the arm 48 to pass therethrough. Theswivel frame 2 comprises a yoke 10, the arms of which carry the specimen clamp screws i 11 which are constructed and-arranged in a similar manner to the specimen clamp screws 7. The outer end of the yoke is provided with a'threaded er:-` tension 12 vand an annular shoulder 13 which is rotatable on the bearing face 14 on the under side of the strut 3. The strut is recessed onits top face, as indicated at 15, in order to adapt it to receive the lower frame nut 16 which engages the threaded extension 12 and bears against the shoulder or E( nge 17 so that a swivel connection is vformed between the liXed frame andthe strut. Y

18 designates an indicator cup which consists ofa plate 19 having an annular flange 4 represents a section on line 4-4 of in which is securely held the annular base of the indicator 21 which may be of any desired or conventional construction and is provided with a d-ial 22 and a pointer 23. The pointer 23 is connected to a plunger 24 which passes through an aperture 25 in the plate 19 and an aperture 26 in the swivel frame so that the arm 8 bears against the end of such plunger. The plate 19 issecured to the strut 3 by means of fastening devices 27 which pass through the slots 28 in the plate 19 and into threaded engagement with the strut 3.

The slots 28` provide for the proper centering ofthe plunger 24 kin the aperture 26. The strut 3 at its upper end is preferably recessed, as indicated at 29, in order that it will not interfere with the specimen 30 which is to be stressed. The upper end of the strut 3 is upwardly deflected, as indicated at 31,l to form a clip. Such clip is preferably provided with an inward projection 32 to limit the movement of the movable frame. The movable frame is in the form of a bell crank lever pivoted to the strut and having its short arm Vattached tothe specimen and its long arm resting against the plunger of the indicatingdial.

A swivel; connection between the fixed frame and the strut is employed to enable oneV to determine the stretch on both sides of the specimen. In many cases, a specimen is of harder` material on one .side than it is on the other, and' due to thisl swivel action,

ksuch condition can be taken care of and the instrument is not strained and the exact stretch between the two points can be `accurately determined. Y

Referring now to Figs. 5, 6 and 7, I will describe the double pointed marking block which is employed to accurately and quickly mark the specimen. the required distance apart and at opposite ends of a diameter ready to receive the extensometer. This marking block comprises the block sections 33v and 34k which are alined with respect to each other by means of the dowel pins 35. Each block sectionis constructed in a' similar manner and is provided with a V-shaped groove 36 and with `the lugs or bosses 37 at each end through which pass the marking punches 38. Each punch 38 is provided with a longitudinally extending recess 39 into which extends a set screw 40 which is in. threaded engagement with a lug or boss In the operation, the specimen to be stressed is iirst laced in the marking block, as seen in Fig. The punches 38 are then driven toward the specimen so that at opposite ends it is marked at diametrically opposite points and the specimen is now ready to be placed in the eXtensometer. The operator grasps the clip 31 and the ring 9 with his thumb and foreiinger so that when pressed together the points of attachment are brought the proper distance apart for quick and convenient yattachment to-the specimenby the clamp screws 7 and l1. It will be apparent that as the specimen is stressed and the? distance between the clamp screws 7 and 11 changed, the bell crank lever or movable frame will multiply the motion and thus cause a properly constructed dial to indicate the amount of the movement.

It will now be apparent that I have devisedl a novel and useful eX-tensometer, which embodies the features of 'advantage enumerated as desirable in the statement, of the invention and the above. discri-ption, and while I have, in the presentl instance, shown and described a typical embodiment of it which will givein practice satisfactory and reliable results, it is to be understood that this embodimentiis susceptible` ofy mod-i? iication in various partcula-rs without departing from the spirit or scope of the inf vention or sacrificing anyv o its advantages.

Having thus described my invention, what I claim as new and desi-re to secure byv Letters Patent, is

1. In an ex-tensometer, in combination, a strut, a fixed frame carried by said strut, an indicator carried by said strut and provided withv an actuating plungenand a bell crank lever fulcrumed in said strut and having one arm provided with opposed specimen. clamping members adapted Vto be connected to the specimen to bel stressed andA itsY other arm to engage said plunger.`

2. In an extensometer, in combination, la strut, a fixed frame swivels/d in it, an indicatorcarried by said strut and providedwith an actuating plunger, and aV bell crank lever fulerumed` in saidl strut and vhaving one arm adapted to beconnectedfto the-specimen to be stressed and; its other arm to engage said" plunger.

3. In an extenscmeter, a strut, 'a fixed frame carried by said strut, an indicati-ng device carriedby said-v strut and providedI with an actuating plunger, and a bell cra-nic lever fulcrumed in said strut* and; having'its short arm providcdwith opposed specimen clamping members adapted to be connected to the specimen and' its longarmto engage said plunger.

4. In an extensometer, a strut, aV fixed frame carried by Vsaid strut, means to secure said fixed frame to the specimen, a movable frame fulcrumed' in said strut, means carried by said movable frame to clamp` it to the` specimen, and indicatingmechanism carried by the strut and actuated by said movable frame. f v

5. In an vextensometer, a strut, a xed frame rotatably carried by said strut,means to secure said xed frame to the specimen, a frame fulcrumed to said strut and having means to connectit to a specimen, 1 and in- ISILO dicating mechanism carried by the strut and actuated by said frame..

6. In an extensometer, a strut, a fixed frame carried by said strut, means to secure said fixed frame to the specimen, a frame fulcrumed to said strut and having means to engagea specimen, and' indicating mechanism adjustably mounted on said strut and actuatedby said frame.

7. In 'an extensometer, a strut, a fixed frame swiveled therein, imeans to secure said fixed frame to the specimen, a bell crank lever fulcrumed in said strut and adapted to be connected to a specimen'and provided with a finger engaging portion, and indicating mechanism carried by the strut and actuated by said bell crank lever.

8. In an extensometer, a strut, a fixed frame carried thereby, means to secure said fixed frame to the specimen, a bell crank lever fulcrumed in said strut and provided with means to engage a specimen and provided with a finger engaging portion, said strut having a clip thereon, and indicating mechanism carried by said strut and actuated by said bell crank lever.

9. In an extensometer, a strut, a fixed frame carried thereby at one end of the strut, means to secure said fixed frameto the specimen, a bell crank lever Julcrumed at the other end of said strut and having its short arm adapted to engage a specimen,

said strut having a defiected portion to form a bearing for the thumb of the operator, said bell crank lever having a finger engaging portion, and indicating mechanism carried by said strut and actuated by the long arm of said bell crank lever.

10. In an extensometer, a strut, a fixed frame carried by it, means to secure said fixed frame to the specimen, a nut engaging said xed frame to secure it in position, a support for indicating mechanism adjustably carried by said strut, indicating mechanism carried by said support and having an actuating plunger, and a bell crank lever fulcrumed in said strut and having its short arm adapted to be connected with the specimen and its long arm adapted to actuate said plunger.

11. In an extensometer, a strut, a fixed frame carried by it, means to secure said xed frame to the specimen, a nut engaging said fixed frame to secure it in position, a support for indicating mechanism adjustably carried by said strut, indicating mechanism fastened to said support and having an actuating plunger, and a bell crank lever fulcrumed in said strut and having its short arm adapted to be connected with the specimen and its long arm adapted to actu'ate said plunger.

12. In an extensometer, a strut, a fixed frame swiveled therein, means to secure said fixed frame to the specimen, indicating mechanism carried by said strut and having an actuating plunger extending through said fixed frame, and a bell crank lever fulcrumed in said strut having its short arm adapted to be connected to the specimen and its long arm to engage said plunger.

13. In an extensometer, a strut, a fixed frame swiveled therein, means to secure said fixed frame to the specimen, indicating mechanism carried by said strut and having an actuating plunger extending through said fixed frame, and a bell crank lever ulcrumed in said strut having its short arm adapted to be connected to the specimen and itslong arm passing through said strut and bearing against said plunger.

14. In an extensometer, a xed frame comprising a yoke and a threaded extension, a strut in which said threaded extension is swiveled, clamping screws carried by said yoke, a bell crank lever having one end in the form of a yoke fulcrumed 1n said strut, clamping screws carried by the yoke of said bell crank lever, and indicating mechanism carried by said strut and actuated by said bell crank lever. y

15. In an extensometer, a fixed frame comprising a yoke and a threaded extension, a strut in which said threaded extension is swiveled, diametrically opposed clamping screws carried by said yoke, a bell crank lever having one end in the form of a yoke fulcrumed in said strut, diametrically opposed clamping screws carried by the yoke of said bell crank lever, and indicating mechanism carried by said strut and actuated by said bell crank lever.

WILLIAM J. TRETCH.

Witnesses:

I-I. S. FAIRBANKS, C. D. MoVA'r.

Copies of this patent may be obtained for iive cents each, by addressing the Commissioner of Patents. Washington, D. C. 

